Ch. 10, Hearing Flashcards
sound waves
stimulus for audition
mechanica stimulus
waves of compression and rarefaction (opposite of compression, decompression)
amplitude
meausirng from top to bottom on a sound wave
3 physical properties of sound waves
frequency: number of cylces per second, measured in Hz
2. amplitude, stimulus intensity/strength
3. complexity: mix of frequencies and amplitudes present in a single waveform
waveform
more complex?
frequency
produces pitch perception, the rate at which sound waves vibrate
amplitude
produces our perception of loudness, measured in decibals (dB)
magniotuder of change in air molecule density
every 10 decibal increase = 10x louder
100 or more decibals will cause permanent hearing damage after 15 minutes
complexity
produces timbre, perception of sound quality, allows us to distinguish between diff sounds
whales and dolphins
hear lower and higher freuqencies thanus
soft sounds vs loud sounds
soft: 20 decibals
loud sound: 70 decibals
sound wave complexity; Pure tones vs complex tones; fundamental frequency vs overtone
pure tones: sounds with single frequency
complex tones: sounds with a mixture of frequencies
fundamental frequency: lowest frequency of complex waveform?
overtone: everything else that is not fundamental; An overtone is a resonant frequency that is higher than the fundamental frequency of a sound. Overtone frequencies are whole-number multiples of the fundamental frequency. For example, if the fundamental frequency is 131 Hz, then the first overtone would be 262 Hz, the second overtone would be 393 Hz, and so on.
outer ear structures and 3 functions
pinna: acts like a funnel to collect sound
external ear canal: The external auditory canal, or ear canal, focuses sound waves onto the eardrum, or tympanic membrane, for further transmission:
The external ear’s functions include:
1. Amplification
The external ear can amplify sound pressure
2. Sound localization
The pinna and concha filter different sound frequencies to help determine the elevation of the sound source.
3. Protection
The ear canal contains ceruminous glands that produce earwax to help keep insects and debris out.
middle ear structures
EARDRUM IS PART OF MIDDLE EAR
ossiciles: hammer (malleus), anvil (incus), stirrup (staples): vibrate at the same frequency of sound waves, The auditory ossicles—malleus, incus, and stapes—are three small bones in the middle ear that transmit air vibrations from the outer ear into the inner ear, so they can be processed as sound.
OVAL WINDOW IS ALSO MIDDLE EAR
bipolar neurons
sensory neurons thsat make up the auditory nerve
organ of corti, cochlea
includses basilar membrane: narrow, thick base: processers high frequency
wide thin top: processes lower frequencies
sound waves at medium frequency are processed in middle
outer hair cells: motor function, not auditory
inner hair cells: auditory
tectorial membrane
cilia
In the auditory system, cilia are hair cells in the inner ear that convert sound waves into electrical impulses that travel to the brain:
basilar membrane, cochlea
narrow, thick base: processers high frequency
wide thin top: processes lower frequencies
sound waves at medium frequency are processed in middle
tenoitis
ringing or buzzing in ear, due to death of inner hair cells (could be caused by something else)
what happens when the cilia on inner hair cells bend?
graded potentials are generated, which affects the firing rate of auditory (cochlear) nerve neurons= how sound gets transduced
movement of cilia toward tallest cilia vs shortest
activates stretch activated channels, Ca2+ permeable = depolarization and more NT release, activity in auditory nerve increases
Movemeent of cilia toward shortest: hyperpolarizes the cell, activity in auditory nerve neurons decrease
pathway to A1 from left ear
- left ear (left auditory nerve)
- l;eft medulla in hindbrain
- crosses to right hemisphere
- right inferior colliculus
- LEFT AND RIGHT MGL
- Gets processed by both hemispheres and both A1 sides
heschl’s gyrus
primary auditory cortex and A1
larger in right hemisphere,m role in analyzing music
Wernicke’s area
p[lanum temporale
posterior speech zone
regulates language comprehension
damaged=can’t understand
MUCH LARGER IN LEFT SIDE
lateralization
difference in function between inferior and superior colliculus
The superior colliculus receives input from the retina and the visual cortex and participates in a variety of visual reflexes, particularly the tracking of objects in the visual field. The inferior colliculus receives both crossed and uncrossed auditory fibres and projects upon the medial geniculate body,
what influxes into the cell when cilia move toward the shortest one
function of tectorial membrane in organ of corti (more specifically the cochlea)
-Amplifying auditory stimuli
Supporting traveling waves: The TM reinforces traveling waves of vibration, which helps to accurately represent a sound.
-Ensuring optimal cochlear feedback
-The TM ensures that the gain and timing of cochlear feedback are optimal.
Mediating hearing sensitivity
The TM influences its local environment to mediate hearing sensitivity.
primary function of cilia
Sound detection: Sound waves cause the eardrum to vibrate, which moves the cilia, or hair cells, in the inner ear. The cilia then send electrical impulses to the brain through the auditory nerve.
Clearing earwax: Cilia move earwax through the inner ear to keep the ear canal open.
Balance: Cilia act as motion sensors to monitor fluid in the ear and help the brain maintain balance.
function of the sclera
Protecting the eye
Maintaining the eye’s shape
Anchoring muscles
Providing channels for blood vessels and nerves
function of optic radiations
The optic radiations are a projection tract that connects the lateral geniculate nucleus to the primary visual cortex in the occipital lobe. It functions to transmit visual input coming from the retina, the optic nerve, and the optic tract.
difference between rarefaction and compression
Compression
A region of high pressure and density in a sound wave where air molecules are squeezed together
Rarefaction
A region of low pressure and density in a sound wave where air molecules are pulled apart
steps through the auditory system
- pinna catches sound waves = deflects them into the external; ear canal
- waves are amplified = directed to eardrum
- Ossicles vibrate: then amplify and convey vibrations to the oval window
- Oval window (MIDDLE EAR) causes cilia of inner hair cells to bend = generates neural activity in hair cells
- Basilar membrane and tectorial membnrane bend
- causes vibration of oval window that sends waves through cochlear fluid
tonotopic map
Tonotopic map represented
on the basilar membrane
- spatial arrangement of
frequencies for which
it is tuned to
How is pitch perceived and processed
pitch is porocessed by A1 in tonotopic fashion;
higher frequency = base of chochlea
lower frequency: top of cochlea
What impact does a larger amplitude have on the auditory system?
largewr amplitude= increase of puressure changes and more vibrations in the basilar membrane = greater displacement of the membrane = greater displacement of inner hair cells (resulting in movement toward the tallest cilia, = more NT releasedfrom inner hair cells onto bipol;ar, sensory neurons= net depolarization )
Pathway for understanding speech
- A1
- Wernicke’s area, contains “mental images” of word sounds, processes phonemes
= comprehension
Arcuate fasiculus
fasiculus means it connects something within the same hemisphere, callosum means it connects something BETWEEN hemispheres
WHITE MATTER; connects wernicke’s and broca’s area
broca’s area
speech production / language production, left hemispere, frontal lobe, anterior to central sulcus, motor bc produces the facial/tongue movements for speech
anterior vs posterior to central sulcus
posterior= sensory
anterior = motor
pathway for producing speech
wernickes area: plans for meaningful speech
2. broca’s area, stores motor programs for speaking words
3. facial area of motor cortex
4. cranial nerves
= speech
difference between wernicke’s aphasia and broca’s aphasia
broca’s aphasia: inability to speak fluently despite presence of normal comprehension and intact vocals, MUCH MORE DISTRESSING BC THEY CAN UNDERSTAND BUT NOT TALK
wernicke’s aphasia: inability to understand or produce MEANINGFUL SPEECH, even though word production remains intact, its not meaningful, might not even be aware of their deficits, less distressing,
effective communication strategies for broca’s aphasia
boards with objects; point to what you want
; melodic intonation: singing can sometimes remain unaffected, bc this would be more right hemisphere and heschl’s gyrus takes over
reading might be unaffected, but writing ma be limited
wernicke’s aphasia and degrees of nonverbal communication
minor: making semantic errors
extreme: inventing new words, doesn’t make any sense, abnormal repetition, impared reading and writing
wavelength
The wavelength of a wave is the length in meters from the start to the end of one full cycle of the waveform e.g. from crest to crest.
divisions of inner ear
he inner ear has two main parts. The cochlea , which is the hearing portion, and the semicircular canals is the balance portion.
organ of corti: INSIDE THE COCHLEA, contains the basilar membrane, tectorial membrane, inner/outer hair cells
